Subclinical carotid vascular disease and risk factors for atherosclerosis in type 1 and type 2 diabetes

T he association of diabetes mellitus, both type 1 (T1DM) and type 2 (T2DM), with increased cardiovascular risk is well known (1), but growing evidence has shown a wide heterogeneity in the risk of cardiovascular events in diabetics.Besides clinical evaluation, assessment of subclinical vascular disease, such as screening for coronary artery calcium (CAC), a surrogate marker of atherosclerosis in those with normal renal function, and carotid intimal-media thickness (CIMT), can further stratify risk in diabetics, identifying higher and lower risk groups (2).In a sub-study from MESA (Multi-Ethnic Study of Atherosclerosis), for instance, the cardiovascular event rates in individuals with metabolic syndrome or T2DM were as low as in those without these conditions, unless CAC or CIMT were significantly elevated.In this issue of Archives of Endocrinology and Metabolism, two studies unravel the predictors and risk associated with elevation of CIMT and presence of carotid plaque in two distinct groups of diabetic patients.While a universal concept of "cardiovascular risk equivalent" for the entire diabetic population has been progressively replaced for a more selective categorization within this group, understanding the utility of subclinical disease markers in this context, particularly subclinical carotid disease, still lacks further evidence.In the first study in this issue, Kupfer and cols.(3) assessed the clinical predictors of subclinical carotid vascular disease in asymptomatic young adult women with T1DM.Of importance, cardiovascular events are more common and occur earlier in patients with T1DM compared to non-diabetics, particularly in women.In the General Practice Research Database (GPRD) from the UK, with over 7,400 T1DM patients and mean DM duration of 15 ± 12 years, T1DM male patients presented an absolute cardiovascular risk similar to that of men from general population 10-15 years older; type 1 diabetic women had an even greater risk compared to their non-diabetic counterparts (4).Therefore, young female type 1 diabetics, evaluated in the study by Kupfer and cols.(3), represent a subgroup that might benefit more importantly from preventive strategies, especially if they already present at a young age any sign of incipient atherosclerosis.In this study, 45 asymptomatic type 1 diabetic women, still young (mean age 36.2 ± 9.5 years), but with already a long-term DM duration (mean 18.1 ± 9.5 years), exhibited a mean CIMT of 0.25 mm, with presence of carotid plaques in 13%.CIMT, as measured by carotid artery ultrasonography, is the distance from the lumenintima interface to the media-adventitia interface of the artery wall.The presence of carotid plaque is defined usually as an intima-media thickness of more than 1.5 mm.Unless there is a media layer hypertrophy due to uncontrolled hypertension, CIMT is usually recognized as a surrogate measure of atherosclerosis, and an independent predictor of cardiovascular outcomes (5).Moreover, the maximum IMT of the internal